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E. LDUBEY.

ENVELOPE.

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EDlVARI) A. DUBEY, OF BROOKLYN, NEW YORK, ASSIGNOR OF ONE-HALF A TO JAMES LANGAN, OF SAME PLACE.

ENVELOPE.

SPECIFICATION forming part of Letters Patent No. 443,611, dated December 30, 1890.

Application filed December 16, 1839. Serial No. 338,849. (No model.)

To all whom it may concern:

Be it known that I, EDWARD A. DUBEY, of Brooklyn, county of Kings, State of New York, have invented certain new and useful Improvements in Envelopes, of which the following is a specification.

My invention relates to envelopes so constructed as to render clandestine opening impossible; anditconsistsin certain details of imro provement andin combination of parts, which will be more fully set forth in the subsequent specification, reference being had to the accompanying drawings, forming part thereof, whereinr 5 Figure 1 represents the envelopeblank spread open. Fig. 2 represents a back view of myimproved envelope, the tongue D being shown turned down. Fig. 3 represents a back view of my envelope sealed.

2o My blank is cut in shape of an ordinary envelope-blank, with the addition of the tongue D to the lower flap C. This tongue D has a series of fine perforations h, of any convenient shape, the perforations being placed in 2 5 close proximity to one another, some being narrow parallel slits running vertically or in any other direction, some star-shaped openin gs; but any other suitable shape may be imparted to these closely-placed perforations.

0 This tongue D is intended to be folded down against the inner side of the bottom flap 0. Out of the bottom flap O, I form by a substantially V-shaped incision another tongue 2', which is so situated that the perforated part of the tongue D will 'lie behind it when the envelope is formed. Any number of similar incisions and tonguest' may be so constructed as to fold upon the upper flap E. This tongue 1' is surrounded by slits and per- 0 forations 107s, that are also placed close together to weaken the paper between them, and that are so arranged that when the bottom flap C is folded upon the side flaps A and B they will be in position to be covered by the top or seal flap E. The side flaps A B also have slits and perforations jj', of any convenient shape, placed close together to weaken the paper between them, and so located that they will finally be covered by the seal-flap E. The seal-flap E is cut vertically at the pointsl I, so that when folded down the lip m, paving perforations and slits p'betwcen the slits Z Z, is pasted on the perforated part h of the tongue D, and finally the tongue t' is pasted upon the lip on and slitsZ Z, thus forming a double seal. The upper flap E is. covered along its inner face with adhesive substance, which when folded will fall exactly on the perforations and slits 75 7c and j j. The perforations 70 k, j j, and h are so arranged that when the upper flap E is sealed upon them it takes sufficient hold to keep the envelope closed, and yet these slits and perforations are so, narrow and small that none of the adhesive substance is forced through into the inclosed matter. When this envelope is opened clandestinely the fact is easily detected, as the numerous points and narrow pieces of paper presented for contact with the adhesive substance will hold some particles of such substance, and as they are so weak that some of them will necessarily be ruptured in opening, and when the envelope has been clandestinely opened by means of steam or otherwise and is again sealed the adhesive substance will now enter the larger openings formed by the tearing, and will cause the letter to be gummed fast to the envelope, thus proving the fact that the package has been tampered with.

The slits n n and 0 o are employed for the detection of the introduction of any sharp instrument, for when gummed fast to the sealflap E the instrument will pass into the slit or n, and the space between n n o o be ing fast at all intermediate points will be torn out by forcing the instrument in any direction, as the paper in these spaces is weakened by the slits and perforations jj. Therefore,

Having fully described my invention, what I claim, and for which I pray Letters Patent,

1. In an envelope, the lower flap 0, provided with the outwardly-projecting tongue D and with the inner tongue 1', projecting in 5 the same direction as the tongue D and adapted to be folded over the upper fiap,substantially as specified. I

2. In an envelope, the tongue '2', out subst-antially V-shaped from the body of the lower IOO flap O, in combination with the lip m, having perforations and slits 19 between the slits Z Z,

out in the upper or seal flap 1C, substantially and the tongue 71, out substantially V shape 10 for the purposes specified. from the body of the lower flap the perfo- 3. A11 envelope having the upper 01' seal rations and slits h falling on the incision of flap E,bea.1ing' the lip m,hmZ ili 1g perforations the tongue 1 substantially as described. 5 and slits 1) between the slits the side fla s s T p T a A and B, bearing the slits and perforation j ARI) and the slits n n 0 0, the bottom flap U, Witnesses: having the tongue D, bearing slits and per- HENRY E. EVERDIN forations "it, turned down behind said flap HARRY M. TURK. 

